Beard Dermal Papilla Cells Research Articles

Gene expression profile in frontal and beard dermal papilla cells

1. Moonkyu Kim, MD, PhD, 2. Jung-Chul Kim, MD, PhD 1. Daegu, Korea Frontal and beard dermal papilla cells appear to be very different at the resting state and respond differently to dihydrotestosterone stimulation. While beard dermal papilla cells (probably through the activation of Wnt)

Androgen Receptor Co-Activator Hic-5/ARA55 as a Molecular Regulator of Androgen Sensitivity in Dermal Papilla Cells of Human Hair Follicles

Androgen site-specifically affects human hair growth after puberty through androgen receptors in the dermal papilla, which transactivate target genes acting in conjunction with co-activators. To examine the regulation of androgen sensitivity in hair follicles, we focused on androgen receptor co-activator Hic-5/ARA55. Its interaction with transfected androgen receptor in beard dermal papilla cells was confirmed with mammalian two-hybrid assays. The semiquantitative reverse transcriptase-polymerase chain reaction showed that Hic-5/ARA55 mRNA expression was high in dermal papilla cells from the beard and bald frontal scalp but low in cells from the occipital scalp. To determine whether Hic-5/ARA55 mRNA level correlates with its endogenous activity, we studied the effect of dominant negative Hic-5/ARA55 on transfected androgen receptor transactivation induced by R1881 using mouse mammary tumor virus-luciferase assays. We found that it suppressed the transactivation by 64.5 and 71.4% in dermal papilla cells from the beard and bald frontal scalp, respectively, whereas it showed no significant effect in cells from the occipital scalp. Our findings suggest that Hic-5/ARA55 is a molecular regulator for androgen sensitivity in human hair follicles.

Differences in Expression of Specific Biomarkers Distinguish Human Beard from Scalp Dermal Papilla Cells

Androgen exposure stimulates the growth of beard hair follicles. The follicle dermal papilla appears to be the site of androgen action; however, the molecular mechanisms that regulate this process are not well understood. In an attempt to identify genes that contribute to the androgen-responsive phenotype, we compared gene expression patterns in unstimulated and androgen-treated cultured human dermal papilla cells isolated from beard (androgen-sensitive) and occipital scalp (androgen-insensitive) hair follicles. Through this analysis, we identified three genes that are expressed at significantly higher levels in beard dermal papilla cells. One of these genes, sfrp-2 has been identified as a dermal papilla signature gene in mouse pelage follicles. Two of these genes, mn1 and atp1beta1, have not been studied in the hair follicle. A fourth, fibulin-1d, was slightly upregulated in beard dermal papilla cells. The differences in the expression of these genes in cultured beard and scalp dermal papilla cells reflected similar differences in microdissected dermal papilla isolated from intact beard and scalp follicles. Our findings introduce potentially novel signaling pathways in dermal papilla cells. In addition, this study supports that cultured dermal papilla cells provide a cell-based model system that is reflective of the biology of in vivo hair follicle cells.

The Modulation of Aromatase and Estrogen Receptor Alpha in Cultured Human Dermal Papilla Cells by Dexamethasone: A Novel Mechanism for Selective Action of Estrogen via Estrogen Receptor Beta?

Steroid hormones have important modulatory effects on the hair follicle, but the mechanisms by which they regulate human hair growth are still poorly understood. It is now clear that there are two distinct estrogen receptors (estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta)) that bind 17beta-estradiol. Since the follicular dermal papilla is known to control hair growth, and steroid hormones regulate receptor and aromatase expression in other tissues, we tested the hypothesis that steroid hormones would similarly modulate estrogen receptor and/or aromatase expression in cultured dermal papilla cells derived from human hair follicles. Primary cultures of non-balding occipital and frontal scalp and beard dermal papilla cells (n = 10) were established. Immunocytochemical studies showed the expression of ERalpha in both the cytoplasm and nucleus, whereas ERbeta was confined to the nuclei. The cells derived from occipital scalp were also incubated for 24 hours with 10 nM of either 17beta-estradiol, estrone, testosterone, 5alpha-dihydrotestosterone, 5alpha-androstane-3alpha, 17beta-diol, 5alpha-androstane-3beta, 17beta-diol, or 100 nM tamoxifen or dexamethasone in phenol red-free, serum-free medium to measure the steady-state levels of ERalpha, ERbeta, and aromatase mRNA by semiquantitative reverse transcriptase-PCR. Although androgens and estrogens did not alter ERalpha mRNA levels, treatment with dexamethasone significantly reduced ERalpha levels to 38% of the untreated control. By contrast, ERbeta mRNA levels were unaffected by any steroid treatment. Furthermore, dexamethasone significantly stimulated the expression of aromatase mRNA approximately 9-fold. Aromatase activity, assayed by the tritiated water method, was stimulated in both frontal scalp and beard dermal papilla cell cultures by dexamethasone. These observations provide evidence for a glucocorticoid-dependent mechanism whereby the selective action of estradiol via ERbeta may be promoted. Additionally, upregulation of aromatase combined with downregulation of ERalpha provides a basis for selective action of estradiol produced locally by autocrine or paracrine mechanisms.

Role of Androgen in Mesenchymal Epithelial Interactions in Human Hair Follicle

Human hair follicles, which are distributed in various and specific sites of the body, appear to have an inherited susceptibility for androgen-dependent growth. Beard, axillary, and frontal scalp dermal papilla cells (DPC) were recently shown to possess the characteristics of androgen target cells. These DPC show strong expression of androgen receptors, and the expression of type II 5alpha reductase is restricted to beard and frontal scalp DPC. These findings suggest that DPC mediate the signals of androgen to follicular epithelial cells in a paracrine fashion. We developed an in vitro co-culture system using DPC and keratinocytes (KC) to characterize the mode of androgen action in human hair follicles. Androgen significantly stimulated the proliferation of KC co-cultured with beard DPC, indicating that beard DPC produce androgen-dependent diffusible growth factors. Insulin-like growth factor-I was identified as one of the androgen-dependent paracrine growth factors produced by beard DPC. We also identified the inhibitory role of androgen on the growth of KC co-cultured with DPC from androgenetic alopecia (AGA) when the DPC were transfected with an expression vector encoding the androgen receptor. This growth suppression of KC was mediated by transforming growth factor-beta1 (TGF-beta1) derived from DPC of AGA, suggesting that TGF-beta1 is a paracrine mediator for AGA.

Male androgenetic alopecia

Male pattern hair loss is the most common cause of balding. The pathogenesis involves androgen, and in particular dihydrotestosterone, binding to androgen receptors in the dermal papilla of sensitive hair follicles. Hair follicle sensitivity is genetically determined and shows regional specificity. Androgen stimulation of scalp dermal papilla cells induces transforming growth factor beta (TGF-B) and results in cyclical miniaturization of the entire hair follicle. The resulting hair produced from that follicle is shorter and finer and provides less complete scalp coverage. In contrast androgen stimulation of beard dermal papilla cells produces insulin growth factor -2 (IGF-2) and results in cyclical enlargement of the entire hair follicle. The resulting hair produced from that follicle is longer and thicker and provides more complete facial skin coverage. Some degree of androgenetic alopecia is universal among ageing men, especially bitemporally, however less than half become bald in the Hippocratic sense. Although scalp hair coverage has little functional importance, it has cosmetic significance. Baldness changes the facial appearance of affected men. When that change is perceived as adverse it has the potential to produce emotional morbidity.

高齢者の健康増進におけるトランスレーショナルリサーチ―エビデンスに基づく高齢者の健康増進への戦略―１．男性型脱毛の発症メカニズムと治療選択

Hair follicles are composed primarily of epithelial and dermal components that develop from embryonic ectoderm and mesoderm respectively. The hair growth cycle is coordinated with complex processes that are dependent on the interactions of epithelial and dermal components. Beard and frontal scalp dermal papilla cells (DPCs) show the characteristics of androgen target cells. These DPCs expressed androgen receptor and type II 5alpha-reductase mRNA. To understand the mode of androgen action in human hair follicles, we developed an in vitro co-culture system using DPCs and follicular keratinocytes. Androgen significantly stimulated the proliferation of keratinocytes co-cultured with beard DPCs, suggesting that these DPCs produce androgen-dependent diffusible growth factors. Insulin-like growth factor-I (IGF-I) was identified as one of the androgen dependent paracrine growth factors from beard DPCs. On the other hand, we identified inhibitory roles of androgen on the growth of keratinocytes co-cultured with DPCs from human balding frontal scalp, when DPCs were transfected with the AR expression vector. This inhibitory effect was mediated by TGF-beta1 from the DPCs. Minoxidil and Finasteride were recently introduced for the treatment of androgenetic alopecia in Japan, and TGF-beta1 is the next target for innovative treatment.

男性型脱毛の発症メカニズムと治療戦略

Hair follicle is composed primarily of epithelial and dermal components that develop from embryonic ectoderm and mesoderm respectively. Hair growth cycle is coordinated and complex processes that are dependent on the interactions of epithelial and dermal components. Beard and frontal scalp dermal papilla cells (DPCs) were recently shown to possess the characteristics of androgen target cells. These DPCs expressed androgen receptor and type II 5α-reductase mRNA. To know the mode of androgen action in human hair follicles, we developed an in vitro coculture system using DPCs and follicular keratinocytes. Androgen significantly stimulated the proliferation of keratinocytes cocultured with beard DPCs, suggesting that these DPCs produce androgen-dependent diffusible growth factors. Insulin-like growth factor-I (IGF-I) was identified as one of the androgen dependent paracrine growth factors from beard DPCs. On the contrary, we could identify inhibitory roles of androgen on the growth of keratinocytes cocultured with DPCs from human balding frontal scalp, when DPCs were transfected with the AR expression vector. The inhibitory effect was mediated by TGF-β1 from the DPCs. Minoxidil and Finasteride were recently introduced for the treatment of androgenetic alopecia, and TGF-β1 is a next target for the innovative treatment.

Expression of mRNA for androgen receptor, 5alpha-reductase and 17beta-hydroxysteroid dehydrogenase in human dermal papilla cells.

In order to determine whether adrenal and gonadal weak androgens are utilized to form active androgens in human hair, we studied the expression of mRNA for androgen receptor (AR), 5alpha-reductase and 17beta-hydroxysteroid dehydrogenase (17beta-HSD) in cultured dermal papilla cells (DPCs) from various body sites. AR mRNA was expressed in beard (Be) and axillary hair (Ax) DPCs from both sexes, but only at a low level in DPCs from occipital scalp hair (OS). Type I 5alpha-reductase mRNA was expressed by all DPCs. Type II 5alpha-reductase mRNA was identified in beard DPCs, but was absent from OS and Ax DPCs. Type II 17beta-HSD mRNA was strongly expressed in outer root sheath cells (ORSCs), while DPCs except for male Ax expressed no type II 17beta-HSD mRNA. In contrast, type III 17beta-HSD mRNA was strongly expressed in Be DPCs and Ax DPCs from both sexes; ORSCs showed a low level of expression. Expression of type III 17beta-HSD mRNA was not regulated by androgen in DPCs. These results suggest that the sensitivity of hairs to androgen is partially controlled by the site-specific expression of AR, 5alpha-reductase and 17beta-HSD in DPCs.

Histopathologycal and topical immunologycal changes in alopeciae

Male pattern hair loss is the most common cause of balding. The pathogenesis involves androgen, and in particular dihydrotestosterone, binding to androgen receptors in the dermal papilla of sensitive hair follicles. Hair follicle sensitivity is genetically determined and shows regional specificity. Androgen stimulation of scalp dermal papilla cells induces transforming growth factor beta (TGF-B) and results in cyclical miniaturization of the entire hair follicle. The resulting hair produced from that follicle is shorter and finer and provides less complete scalp coverage. In contrast androgen stimulation of beard dermal papilla cells produces insulin growth factor -2 (IGF-2) and results in cyclical enlargement of the entire hair follicle. The resulting hair produced from that follicle is longer and thicker and provides more complete facial skin coverage. Some degree of androgenetic alopecia is universal among ageing men, especially bitemporally, however less than half become bald in the Hippocratic sense. Although scalp hair coverage has little functional importance, it has cosmetic significance. Baldness changes the facial appearance of affected men. When that change is perceived as adverse it has the potential to produce emotional morbidity.

The Metabolism of Testosterone by Dermal Papilla Cells Cultured From Human Pubic and Axillary Hair Follicles Concurs with Hair Growth in 5α-Reductase Deficiency

Androgens regulate the growth of many human hair follicles, but only pubic, axillary, and scalp hair growth occur in men with 5 alpha-reductase deficiency. This suggests that 5 alpha-dihydrotestosterone is the active intracellular androgen in androgen-dependent follicles, except in the axilla and pubis. Since the dermal papilla plays a major regulatory role in hair follicles and may be the site of androgen action, we have investigated androgen metabolism in six primary lines of cultured dermal papilla cells from pubic and axillary hair follicles; previous studies have shown that beard cells take up and metabolize testosterone, retaining and secreting 5 alpha-dihydrotestosterone. After 24 h preincubation in serum-free Eagle's medium 199, 100-mm dishes of confluent cells were incubated for 2 h with 5 nM [1,2,6,7-3H]testosterone. Media were collected and the cells washed with phosphate-buffered saline and extracted with chloroform: methanol (2:1). After the addition of unlabeled and 14C-labeled marker steroids, the extracts were analyzed by a two-step thin-layer chromatography system; steroid identity was confirmed by recrystallization to a constant 3H/14C ratio. Beard and pubic dermal papilla cells were also incubated for 24 h, and the medium was analyzed at various times. The results from pubic and axillary primary cell lines were similar. In both cells and media the major steroid identified was testosterone, but significant amounts of androstenedione were present, indicating 17 beta-hydroxysteroid dehydrogenase activity; androstenedione was also identified within the cells, but a small amount of 5 alpha-dihydrotestosterone was only identified in one pubic cell line. Beard dermal papilla cells secreted large amounts of 5 alpha-dihydrotestosterone into the medium over 24 h in contrast to pubic cells, which produced only very small amounts. The pubic and axillary cell results contrasts with the observations of pronounced 5 alpha-dihydrotestosterone in beard cells and confirm that androgen metabolism in cultured dermal papilla cells reflects the parent follicle's ability to respond to androgen in the absence of 5 alpha-reductase type II in vivo. This supports our hypothesis that androgen acts on hair follicles via the dermal papilla and suggests that cultured dermal papilla cells may offer an important model system for studies of androgen action.

Androgen Induction of Follicular Epithelial Cell Growth Is Mediated via Insulin-like Growth Factor-I from Dermal Papilla Cells

Androgen significantly stimulates the proliferation of outer root sheath cells that are cocultured with beard dermal papilla cells without cell contact. The expression of insulin-like growth factor I (IGF-I) mRNA in beard dermal papilla cells was stimulated by androgen and antagonized by cyproterone acetate. Outer root sheath cells did not express mRNA for IGF-I either in the presence or absence of androgen. Both of these two types of cells expressed mRNA for IGF-I receptor and the expression was not affected by androgen. Neutralizing antibody against IGF-I antagonized the stimulatory effect of androgen on the growth of outer root sheath cell cocultured with beard dermal papilla cells. These findings suggest that IGF-I is a candidate for androgen induced hair growth factors.

Characterization of 5α-Reductase in Cultured Human Dermal Papilla Cells from Beard and Occipital Scalp Hair

In order to gain a deeper insight into the role of 5 alpha-reductase in the growth of beards in men, we studied some kinetic properties of the enzyme in cell homogenates of cultured human dermal papilla cells from beard and occipital scalp hair. When cell homogenates were incubated with [3H]-testosterone, the 5 alpha-reductase of beard dermal papilla cells exhibited an optimum activity at pH 5.5, whereas the enzyme of dermal papilla cells from occipital scalp hair showed a broad and low plateau between pH 6.0 and 9.0, without a sharp peak. The apparent Michaelis constant of 5 alpha-reductase was 3.3 x 10(-7) M in dermal papilla cells from beard and 2.4 x 10(-5) M in those cells from occipital scalp hair. The apparent Km of 5 alpha-reductase for NADPH was 2.8 x 10(-5) M and 7.6 x 10(-4) M in beard and occipital scalp hair dermal papilla cells, respectively. There were no significant differences in the substrate specificity between these two types of cells. The 5 alpha-reductase activity was recovered mainly in the nuclear fraction of beard dermal papilla cells. By contrast, it was widely distributed among the individual subcellular fractions of dermal papilla cells from occipital scalp hair. These results strongly suggest that these two kinds of dermal papilla cells have different types of 5 alpha-reductase, and that the enzyme in beard dermal papilla cells is similar in characteristics to that in the androgen target organs such as prostate.

5α-Reductase Activity in Cultured Human Dermal Papilla Cells from Beard Compared with Reticular Dermal Fibroblasts

The activity of 5 alpha-reductase was assessed in cultured human beard dermal papilla cells and reticular dermal fibroblasts to elucidate the mechanism of androgen action in promoting the growth of beards in men. The monolayer was incubated with 50 nM of [1,2-3H]-testosterone. Steroids were extracted from the medium and analyzed by thin layer chromatography. The major metabolite in the beard dermal papilla cells was dihydrotestosterone (DHT), the most potent androgen in the androgen target tissue. By contrast, the amount of DHT formed was similar to that of androstenedione in reticular dermal fibroblasts. The 5 alpha-reductase activity in beard dermal papilla cells was three to five times as high as that in the reticular dermal fibroblasts from the same skin sample. The apparant Michaelis constant of 5 alpha-reductase in the beard dermal papilla cells was 1.0 X 10(-6) M, which was virtually equivalent to that of genital skin fibroblasts, typical androgen target cells. It was 4.0 X 10(-5) M in reticular dermal fibroblasts. By contrast, the activities of 5 alpha-reductase in dermal papilla cells from occipital scalp hair follicles were similar to those of reticular dermal fibroblasts of the same skin samples. These results strongly suggest that the beard dermal papilla cell is an androgen target cell, and that DHT plays a role in the growth of beards in men.